If you were to blow on it hard, Gyroporus cyanescens just might bruise blue. This easily recognized mushroom is found under hardwoods in eastern North America, usually in sandy soil (it is especially fond of grassy areas at woods' edges, road banks, and so on). Its straw yellow colors and brittle consistency, together with its strong bluing reactions and yellow spore print, separate Gyroporus cyanescens from other boletes.

Like several other species of Gyroporus, Gyroporus cyanescens has a questionable relationship to trees and may not be mycorrhizal; see the comments under "Ecology," below.

Description:

Ecology: Often reported as mycorrhizal with hardwoods, but, as Singer (1945) notes, it grows "[i]n woods and even on meadows" and "does not seem regularly to form mycorrhiza, at least no preference of any forest tree is shown, and sometimes fruiting bodies are formed far from any tree at all" (see also the discussion of similar ecology for Gyroporus castaneus); growing alone, scattered, or gregariously, usually in sandy soil, especially in disturbed ground (roadbeds, path sides, and so on); summer and fall; fairly widely distributed east of the Rocky Mountains.

Stem: 4-12 cm long; 1-3 cm thick; more or less equal, or swollen; brittle; soon hollowing; colored like the cap or slightly paler; not reticulate; textured like the cap, or nearly bald in age; bruising quickly blue.

According to some authors, Gyroporus cyanescens var. violaceotinctus (described here, if one subscribed to the theory) differs from var. cyanescens by bruising instantly violet blue, without passing through a stage of greenish yellow. According to Bessette, Roody & Bessette (2000), a variety is collected in North Carolina that does not bruise at all.